17-acyloxysteroids and their manufacture

ABSTRACT

The invention concerns novel steroids having valuable properties as anti-inflammatory agents in veterinary and human medicine. The new steroids are 21-desoxyprednisolone 17 Alpha -propionate, -butyrate and -isobutyrate. They are particularly valuable for topical application.

tlnited States Patent Unley et a1.

17-ACY1LOXYSTERO1DS AND THEIR MANUFACTURE Inventors: Peter Oxley; John Rosindale lilousley, both of Nottingham, England Boots Pure Drug Company Limited, Nottingham, England Filed: Jan. 28, 1972 App]. No.: 221,812

Related US. Application Data Division of Ser. No. 613,454, Feb. 2, 1967, Pat. No. 3,639,434.

Assignee:

11.5. C1 424/243, 260/397.45, 195/51 Int. Cl A61k 17/00 Field of Search 260/397.45

References Cited UNITED STATES PATENTS 11/1959 Sarett 260/397.45

OTHER PUBLICATIONS McKenzie et a1., Archives of Dermatology, Vol. 89, page 744, 1964.

Primary ExaminerElbert L. Roberts Attorney, Agent, or FirmLarson, Taylor & Hinds [57] ABSTRACT The invention concerns novel steroids having valuable properties as anti-inflammatory agents in veterinary and human medicine.

The new steroids are 21-desoxyprednisolone 17a-pr0pionate, -butyrate and isobutyrate. They are particularly valuable for topical application.

8 Claims, N0 Drawings l7 ACYLOXYSTEROlDS AND THEIR MANUFACTURE to a method of treating inflammation, especially in- 10 flammation of the skin in animals including man.

According to one feature of the invention there are provided compounds of formula 1 in which R is ethyl, n-propyl or isopropyl.

The compounds of the invention may be prepared by a process which comprises treating a compound of formula I1 11 wherein R is chlorine, Eimirif or arenesulphonyloxy with acetyl nitrate to give a comand thereafter a. replacing the group R by hydrogen, then converting the l7ahydroxy group into the group OCOR and finally reducing the 1 lB-nitrate group to an 11B- hydroxy group; or

b. converting the l7a-hydroxy group into the group OCOR, then reducing the 1 lB-nitrate group to an 1 1B- hydroxy group and finally replacing the group R by hydrogen; or

c. converting the l7a-hydroxy group into the group OCOR,, then replacing the group R, by hydrogen and finally reducing the 1 IB-nitrate group to an 11/3- hydroxy group.

Under certain reaction conditions replacement of the R group by hydrogen and reduction of the 1 lB-nitrate group in steps (b) and (0) may take place simultaneously.

According to another feature of the invention there are provided therapeutic compositions containing as active ingredient a compound of formula 1 in association with a pharmaceutically acceptable diluent or carrier.

The intermediates prednisolone 1 lB-nitrate and those of formula IV CHqRz in which R is hydrogen or bromine and R is hydrogen or the group COR are also novel compounds.

The nitrate ester group of compounds of formula III is introduced by the action of acetyl nitrate, a reagent produced by mixing fuming nitric acid with acetic acid; said ester group is most conveniently transformed into hydroxy by reduction with zinc and acetic acid.

The acylation of the l7a-hydroxy group may be achieved by reaction with an acid anhydride (RCO) O or an acid halide RCOX where X is chlorine or bromine in the presence of a suitable strong acid catalyst. The preferred catalyst is p-toluene sulphonic acid but acids such as perchloric acid are also suitable. The acylation may also be catalysed by bases such as triethylamine. Another method of acylation employs an alka- .noic acid RCOOH in the presence of trifluoroacetic anhydride.

The group R is replaced by hydrogen using conventional methods. For example, a preferred group is the methanesulphonyloxy group which is readily reduced with sodium iodide and acetic acid. When R is chlorine or bromine, the halogen may be replaced by hydrogen using zinc and acetic acid.

The compounds of formula 1 have been found to have valuable anti-inflammatory activity and to be particu larly valuable for topical application. For example we have tested 21-desoxyprednisolone l7a-propionate by the McKenzie test (Archives of Dermatology, 1962, 86, 608-610) and found it to be several times as active as triamcinolone acetonide, a commercially available steroid for topical application. The unacylated steroid, 2l-desoxyprednisolone, however, is virtually inactive in the McKenzie test.

In the following typical reaction schemes, the preparation of the compounds of the invention is illustrated.

The compound Vl may be converted into the 11- nitrate Vll by treatment with acetyl nitrate. This compound may be converted into the 2l-desoxy compound V111, which in turn is acylated to give the 17-acylate 1X. This compound may also be prepared by converting compound V11 into the l7-acylate X, and subsequently treating with sodium iodide in acetic acid to give the compound IX. Compound [X is finally converted into compound XI by treatment with zinc dust and acetic acid. Compound X may also be reduced with zinc and acetic acid to give compound Xll which gives compound X] when treated with sodium iodide in acetic 5 acid. In another modification, prednisolone ZI-acetate (Xlll) may be converted into the llB-nitrate (XlV) which is then hydrolysed to prednisolone llB-nitrate CHQOCO CH3 CHrO COCH:

n no \UOII ozNofw l 11 Acetyl Y KCN/CHQOH i nitrate I O In an alternative process prednisolone I7-acylates (XVI) are converted into the ZI-methane-sulphonates (XII) which are treated with sodium iodide and acetic acid to give the corresponding 2l-desoxy-l7acylates (XI). Alternatively, the compounds XII may be converted into the 2l-chloro-compounds (XVII) by treatment with lithium chloride in dimethylformamide; these compounds are reduced, for example with zinc dust and acetic acid, to give the compounds XI.

CHzOII lCHaS O2Cl CHgOSO2CHa VII NaI/aceti {/moono l acid C CH: O S O zCHa OH H O Y \I/ Acetyl ---b nitrate OH O S O ZCHS Z n/aeetic N aI/acetic acid acid OHIO S O2CH3 CH;

CO R OzNofn ---ocoR OzNOf OQNO T l VIII --OCOR CH2OH J10 JVWO COR IIO I I CH SO2CI O O- In another method of preparation, prednisolone (XVIII) is converted into its 2l-methanesulphonate (VI) which is treated with lithium chloride in dimethylformamide to give the corresponding 2l-chlorocompound (XIX). Treatment with acetyl nitrate gives the l l-nitrate (XX) which is treated with an acid anhydride (R-CO) O in the presence of p-toluenesulphonic acid to give the l7-esters (XXI). Reduction with zinc dust and acetic acid gives the corresponding 2l-desoxy-l7-acylates (XI). Prednisolone 2l-bromide may be converted into the 2l-desoxy-l7-acylates (XI) by a similar process.

CHIOH O OH HO /w/ I CHJSOBCI XVIII CHZOSOQCH: CHgCl O O I OH I OH /\I/ HO l/i \|/k/ l l LiCl/DMF VI XIX Acetyl nitrate CHZCI I on OzNO l /\l/ 0 o I 'OCOR I 000R Ho I I 110 i I Zn/acetic I (R-COhO s- 0- acid 0- XI XXI In a further process compounds of the general formula XI may be prepared by reduction of a 9a-halocompound (XXII) with chromous acetate in the presence of an alkane thiol and preferably in dimethylsulphoxide as solvent.

0 I een R Chromous acetate] 0 butanethiol XXII where R is chloride or bromine and R is as hereinbefore defined.

As a further alternative, similar reactions to those hereinbefore described may be used starting with a A- steriod instead of a A -steroid. The intermediates and final products are then dehydrogenated at C and C by conventional means; for example (a) by microbiological oxidation using organisms such as Corynebacterium simplex, Bacillus sphaericus and Septomyxa affinis, or (b) by chemical oxidation using for example 2,3-dichIoro-5,6-dicyanobenzoquinone.

The preferred compositions according to the present invention comprising a compound of general formula I in association with a pharmaceutically acceptable diluent are those adapted for topical application although the invention is not to be considered to be limited to such compositions. Such compositions may be in the form of liquid solutions or suspensions or in the form of semi-solid creams and ointments.

The compositions may also contain additional therapeutic agents which are compatible with the compounds of general formula I and which are pharmaceutically acceptable. Particularly valuable additional therapeutic agents include antibacterial agents such as neomycin, 2-bromo-2-nitropropane-l,3-diol, 5-chloro- 8-hydroxy-7-iodoquinoline and 5,7-dichIoro-8 hydroxyquinoline.

The following non-[imitative examples illustrate the invention. For convenience, Trade Names are used for certain materials and these are identified as follows:

Florisil Registered Trade Mark for a synthetic magnesia/silica gel adsorbent.

Kieselgel G A Trade Name for a silica gel adsorbent.

Polawax A Trade Name for a polyoxyethylene sorbitan ester emulsifying agent.

Freon 11 A Trade Name for the propellant trichlorofluoromethane.

Freon 12 A Trade Name for the propellant dichlorodifluoromethane.

Freon 114 A Trade Name for the propellant The content of the ingredients of compositions is percent w/w unless there is a statement to the contrary.

EXAMPLE 1 Prednisolone 2l-methanesulphonate (10 g.) was added to a stirred solution of acetyl nitrate at C. prepared from glacial acetic acid (100 ml.) acetic anhydride (100 ml.) and fuming nitric acid (20 ml.). The steroid had dissolved after 1 /2 hours and after 4 hours the mixture was poured into ice/water (1,000 ml.). The product was collected in methylene chloride, the extract was washed with water, dried and evaporated. The residue was crystallised from benzene to give a benzene solvate of prednisolone 2lmethanesulphonate l lB-nitrate, m.p. l75177C. (dec.).

Prednisolone 2l-methanesulphonate llB-nitrate (4 g.) dissolved in acetic acid (80 ml.) was stirred with sodium iodide (8 g.) at room temperature for 1 hour. 5 percent sodium bisulphite solution (80 ml.) was added to the mixture followed by water (80 ml.) until a slight turbidity was apparent. The product crystallised on seeding to give 2l-desoxyprednisolone l lB-nitrate, m.p. 144l45C (dec.). It was used for esterification without further purification.

Toluene-p-sulphonic acid (50 mg.) was dissolved in isobutyric anhydride (2 ml.), 2l-desoxyprednisolone llB-nitrate (500 mg.) was added and the suspension was warmed to 80C. for 30 minutes. The clear solution was cooled and the crystals which separated were collected and washed with ether to give 2l-desoxyprednisolone l7a-isobutyrate llB-nitrate, m.p. l95-l96C JAQLUBMJfi-l" l w Q ml ound; 92.6. 353 H,

7.1. C H NO requires C, 65.3; H, 7.2 percent).

The above compound (400 mg.) was dissolved in acetic acid (20 ml.) and stirred for minutes with zinc dust (2.g.). The mixture was filtered, the filtrate was diluted with water and the product was collected in benzene. The solution was washed with water, evaporated to dryness and the residue was triturated with ether. Further purification by chromatography gave 2 l -desoxyprednisolone l7a-isobutyrate, m.p. 22022lC., [01],, 33.2 (chloroform).

(Found: C, 72.4; H, 8.4. C H O requires C, 72.4; H, 8.3%).

In a similar way there were prepared:

2 l -Desoxyprednisolone 1 lB-nitrate l7a-propionate, m.p. 205C. (dec.). [0:1 69.5 (chloroform). 2 l -Desoxyprednisolone l7a-propionate, 228229C., [01],, 34.0 (chloroform). (Found: C, 72.0; H, 8.2. C H O requires C, 72.0; H, 8.0%).

EXAMPLE 2 Prednisolone l7a-butyrate, m.p. 2172l9C., [01],,

+ l.2 (dioxan, c 0.825) was treated with me- EXAMPLE 3 2l-Desoxyprednisolone llB-nitrate l7a-propionate (445 mg.) was suspended in dry methanol (45 ml.) and the suspension was added to a pre-reduced suspension of palladium oxide (80mg) in dry methanol (l0ml.). The mixture was shaken under hydrogen when l6 ml. was absorbed in 30 minutes. The mixture was filtered, and the filtrate was evaporated to give a gum which was shown to contain 2l-desoxyprednisolone 17apropionate by thin layer chromatography.

EXAMPLE 4 A solution of 2l-desoxyprednisolone llB-nitrate l7a-propionate (0.5 g.) in methylene chloride (25 ml.) was stirred at reflux temperature with tin (2.5 g.) and concentrated hydrochloric acid for 5 /2 hours. This layer chromatography indicated an approximately 40 percent yield of 2l-desoxyprednisolone 17apropionate.

EXAMPLE 5 A suspension of zinc amalgam (2.5 g.) in dioxan (20 ml.) was stirred with cooling until freezing began, cooling was stopped, 2l-desoxyprednisolone llB-nitrate l7a-propionate (0.5 g.) and water (0.5 ml.) were added, and the mixture was stirred at 8-l0C. for 1 hour. Thin layer chromatograms indicated that the major product was 2l-desoxyprednisolone 17ozpropionate.

EXAMPLE 6 Aluminum turnings (5 g.) were amalgamated with 5 percent aqueous mercuric chloride solution and suspended in anhydrous methanol. A suspension of 2l-desoxyprednisolone llB-nitrate l7a-propionate (l g.) in methanol (20 ml.) was added, reaction was initiated by addition of water (0.75 ml.) and dioxan (20 ml.) and the mixture was refluxed for 1 hour. This layer chromatograms indicated partial conversion into 2 l -desoxyprednisolone l7a-propionate.

EXAMPLE 7 Prednisolone Zl-methanesulphonate llB-nitrate (5 g.), sodium iodide (5 g.) and acetone (60 ml.) were refluxed for 45 minutes and the cooled mixture was poured into water. The mixture was extracted with methylene chloride, the clear organic phase was collected, washed with water dried and evaporated to about 10 ml. The solution crystallised on cooling to 0C. to give prednisolone 2l-i0dide llB-nitrate, m.p. l-l76C. (dec.), [01],, 138 (dioxan).

(Found: C, 49.3; H, 5.4;], 24.3; N, 2.5. C H 1NO requires C, 48.9; H, 5.1; I, 24.6; N, 2.7%).

This compound (100 mg.) in dioxan (5 ml.) was stirred with 10 percent aqueous sodium hydrogen sulphite (2 ml.) for 1% hours at room temperature, and then poured into water. The mixture was extracted with methylene chloride, the extract was washed and dried and the solvent was evaporated. The residue was crystallised from ether to give 21-desoxyprednisolone 1 113 nitrate, m.p. 142-147C., identical with material prepared as described in Example 1.

This compound was converted into 2l-desoxyprednisolone 17a-propionate as described in Example 1.

EXAMPLE 8 Prednisolone 2l-bromide (2 g.) was added to acetyl nitrate prepared from acetic acid (20 ml.), acetic anhydride (16 ml.) and fuming nitric acid (4 ml.) at C., the mixture was stirred at 09C. for 1 hour then warmed to room temperature and stirred for 2 hours. The mixture was poured into water, extracted with methylene chloride, the extract was washed with aqueous sodium bicarbonate solution, then water. and dried. The solvent was evaporated and the residue was dissolved in chloroform and percolated through a column of Florisil. The eluate was evaporated and the residue was crystallised from methanol to give prednisolone 21-bromide llB-nitrate, m.p. l89190C., [04],, 149 (chloroform).

(Found: C, 53.7; H, 5,5; Br, 17.3; N, 3.2. C ,H BrNO requires C, 53.9; H, 5.6; Br, 17.1; N, 3.0%).

This compound (884 mg.) was added to p-toluenesulphonic acid (18 mg.) in propionic anhydride (1.8 ml.), chloroform (13 ml.) was added and the mixture was refluxed overnight. The mixture was cooled, stirred for 1 /2 hours with water (8 ml.) and ammonium hydroxide (SG 0.88, 4 m1.) and the solvent layer was collected. It was washed with water, dried, evaporated and the residue was crystallised from acetone to give prednisolone 2l-bromide llfl-nitrate 17apropionate, m.p. 198200C. (dec.), [01],, 101 (chloroform). (Found: C, 55.1; H, 5.7; Br, 15.5; N, 2.6. C H BrNO requires C, 55.0; H, 5.8; Br, 15.2; N, 2.7%).

This compound (200 mg.) in methylene'chloride (8 ml.) was stirred with zinc dust (l g.) at -lOC. during the dropwise addition of a solution of acetic acid (0.27 ml.) in methylene chloride (2 ml.). After minutes at 10C., the solution was kept at room temperature for 10 minutes and filtered. The filtrate was washed with dilute aqueous sodium bicarbonate, then water, dried and evaporated. The residue was purified by preparative layer chromatography and crystallised from methylene chloride/ether to give 2l-desoxyprednisolone l7a-propionate, m.p. 229231C., identical with that prepared by the method described in Example 1.

EXAMPLE 9 A mixture of p-toluenesulphonic acid 100 mg), propionic anhydride (10 ml.) chloroform (70 ml.) and prednisolone 2l-methanesulphonate l lB-nitrate (5 g.), was refluxed for 3 days, cooled and stirred for 1 hours with water (40 ml.) and ammonium hydroxide (SG 0.88, 20 ml.). The solvent layer was collected, washed with water, dried and evaporated. The residual gummy prednisolone ZI-methanesulphonate 11B-nitrate 17apropionate (6.6 g.) in methylene chloride (265 ml.) was stirred at 5C. with zinc dust (33 g.) during the dropwise addition of acetic acid (9 ml.) in methylene chloride (25 ml.). After 30 minutes at 10C. the mixture was warmed to room temperature, left at room temperature for a short time, filtered and the filtrate was washed with aqueous sodium bicarbonate and dried. The solvent was evaporated and the residue was crystallised from methanol to give prednisolone 21- methanesulphonate l7a-propionate, m.p. l34-l37C.

A solution of prednisolone 2l-methanesulphonate l7a-propionate (1 g.) in dimethylformamide (12 ml.) was heated on the steam-bath with sodium bromide (1 g.) for 7 hours, cooled, poured into water, and extracted with methylene chloride. The extract was percolated through Florisil (Registered Trade Mark). Elution was continued with 20 percent acetone in chloroform (200 ml.). The total eluate was evaporated and the residue was crystallised from acetone to give prednisolone 21-bromide l7a-propionate, m.p. 204-205C. (dec.), [011 82 (chloroform).

This compound (200 mg.) in methylene chloride (16 ml.) was stirred with zinc dust (2 g.) at 510C. during the dropwise addition of glacial acetic acid (0.54 ml.) in methylene chloride (4 ml.). After a further 10 min utes at 10C. The mixture was warmed to room temperature for 10 minutes, cooled, filtered and the filtrate was washed with aqueous sodium bicarbonate solution and then water. The dried solution was evaporated and the residue was crystallised from acetone/hexane to give 2l-desoxyprednisolone l7oz-propionate identical with authentic material.

EXAMPLE 10 A solution of p-toluenesulphonic acid mg.) in benzene (50 ml.) was distilled to a volume of 25 ml., 2l-desoxyprednisolone llfi-nitrate (0.5 g.) and propionyl chloride (1 ml.) were added and the mixture was refluxed for 18 hours. The cooled solution was stirred with ammonium hydroxide (SG 0.88, 3 ml.) and water (12 ml.) at room temperature for 30 minutes. The benzene layer was collected, washed with water, evaporated to dryness and the residue recrystallised from ethyl methyl ketone to give Zl-desoxyprednisolone llfl-nitrate 17a-propionate, m.p. 207209C. (dec.), which was identical with the material prepared by the process of Example 1.

EXAMPLE 1l Prednisolone 2l-iodide llfi-nitrate (2 g.) prepared as described in Example 7, was added to a solution of p-toluenesulphonic acid (40 mg.) in propionic anhydride (40 ml.), the mixture was diluted with chloroform (28 ml.) and then refluxed for 21 hours. The cooled solution was stirred with water (16 ml.) and ammonium hydroxide (SG 0.88, 8 ml.) for 15 minutes, the chloro form layer was collected washed with aqueous sodium bicarbonate, aqueous sodium bisulphite, then water, and evaporated to give crude prednisolone 21-iodide l IB-nitrate 17a-propionate.

This crude intermediate (0.8 g.) in dioxan (40 ml.) was stirred for 4 hours with 10 percent aqueous sodium bisulphite 16 ml. The solution was diluted with water (50 ml.), seeded and the crystals were collected, washed with water and dried. The compound was recrystallised from methylene chloride/acetone to give 21-desoxyprednisolone IIB-nitrate l7a-propionate, m.p. 211212C. (dec.). This compound was reduced to 2l-desoxyprednisolone l7a-propionate as described in Example 1. The crude intermediate was also reduced to 2l-desoxyprednisolone 17a-propionate in a single stage process using zinc dust and acetic acid.

EXAMPLE 12 1,9(1 l )-Bisdehydro-17a-hydroxyprogesterone (2 g.) was added to a solution of p-toluenesulphonic acid (40 mg.) in propionic anhydride (4 ml.) diluted with chloroform (28 ml.), and the mixture was refluxed overnight. The cooled solution was stirred with water (16 ml.) and ammonium hydroxide (80 0.88, 8 ml.) for 1% hours, the organic phase was collected, washed with aqueous sodium bicarbonate solution and then water and dried. The solvent was evaporated and the residual oil was crystallised from methanol to give 1,9(11)- bisdehydro-l7a-propionoxy-progesterone, m.p. 199203C., [01],, 30.5 (chloroform).

(Found: C, 75.4; H, 7.5. C H O requires C, 75.4; H, 7.9%).

A solution of this compound (1.46 g.) in methylene chloride (25 ml.) and t-butanol (40 ml.) was treated successively at 27 C. with a solution of 72 percent perchloric acid (0.6 ml.) in water (3 ml.) and a solution of N-bromacetamide (0.65 g.) in t-butanol ml.). After minutes a solution of sodium sulphite heptahydrate (1.6 g.) in water (8 ml.) was added, and the mixture was poured into water. The product was extracted into methylene chloride, the solvent was evaporated at 40C. and the residue was recrystallised from acetone/hexane to give an acetone solvate of 9a-bromo-21- desoxyprednisolone 17a-propionate mp. 191C. (dec.), [al 71 (chloroform).

(Found: C,60.3; H, 7.2; Br, 14.4. C ,H ,BrO 4/3 (C H O) requires C, 60.4; H, 7.1; Br, 14.4%).

A solution of the above solvated compound (520 mg.) and butane-l-thiol (1.1 ml.) in dimethylsulphoxide (17 ml.) was deoxygenated by blowing nitrogen through the solution and then stirred with chromous acetate (700 mg.) under nitrogen overnight. The purple solution was poured into ice-water (200 ml.) and extracted with methylene chloride. The extract was washed with dilute aqueous sodium bicarbonate and then water and dried. The solvent was evaporated and the residual oil was triturated with ether to give a yellow solid. This was purified by preparative thin layer chromatography and finally crystallised from methylene chloride/ether to give 21-desoxyprednisolone 17apropionate, m.p. 23l232.5C., identical with that prepared by the method described in Example 1.

EXAMPLE 13 A mixture of 1,9(11)-bisdehydro-17a-hydroxyprogesterone (2.5 g.), methylene chloride (50 ml.) and t-butanol (80 ml.) was stirred at 27C. and treated successively with 72 percent perchloric acid (1.2 ml.) in water (6 ml.), and N-bromacetamide (1.3 g.) in tbutanol ml.). After 15 minutes, sodium sulphite heptahydrate (3.2 g.) in water (16 ml.) was added and the mixture was poured into water. The solid was col- -lected, washed and dried to give 21-desoxy-9abromoprednisolone, mp 203C. (dec.).

This compound (960 mg.) was added to a solution of p-toluenesulphonic acid (20 mg.) in propionic anhydride (2 ml.) and chloroform (14 ml.) and the mixture was refluxed for 18 hours. The suspension was filtered,

the filtrate was evaporated in vacuo and light petroleum (b.p. 40-60C., 90 ml.) was added to the residue. The gummy solid was collected, purified by preparative thin layer chromatography and crystallised from ethyl 5 acetate to give 2l-desoxy-9a-bromoprednisolone 17apropionate, mp. 180C (dec.), [01],, 80.5 (chloroform). (Found: C, 60.4; H, 6.2; Br, 16.6 C H BrO requires C, 60.1; H, 6.5; Br, 16.7%). lt was converted into 21-desoxyprednisolone 17a-propionate as described in Example 12.

EXAMPLE 14 A mixture of prednisolone 2l-methanesulphonate 17a-propionate (847 mg.), sodium iodide (847 mg.) and acetone (20 ml.) was refluxed for 70 hours, cooled and poured into water. The mixture was extracted with methylene chloride, and the extract was washed, dried and evaporated. The residual gum was purified by preparative layer chromatography and crystallised from acetone/hexane to give prednisolone 2l-iodide 17apropionate, m.p. 163165C. (dec.), [04],, 104 (chloroform).

(Found: C, 55.5; H, 5.9; 1, 24.1. C H 1O requires C, 54.8; H, 5.911, 24.1%).

A solution of this compound (40 mg.) in dioxan (2 ml.) was treated with 10 percent aqueous sodium metabisulphite (0.8 ml.) and left to stand for 2 hours. The solution was diluted with water, the solid when separated was collected and recrystallised from ether to give 2l-desoxyprednisolone l7a-propionate, identical with authentic material.

EXAMPLE l5 Prednisolone 21-iodide 170z-propionate (50 mg.), prepared as in Example 14, in methylene chloride (2 ml.) was stirred at 1011C. with zinc dust (250 mg.) during the dropwise addition of glacial acetic acid (0.07 ml.) in methylene chloride (0.5 ml.). After 10 minutes at 69C. the mixture was allowed to warm to room temperature, filtered and the filtrate was washed with aqueous sodium bicarbonate solution, then water and dried. The solvent was evaporated and the residue was crystallised from acetone/hexane to give 21desoxyprednisolone l7a-propionate identical with authentic material.

EXAMPLE 16 A water miscible cream was prepared containing the following ingredients (percent w/w):

EXAMPLE 17 An ointment was prepared containing the following ingredients (percent w/w):

21-Desoxyprednisolonc 17a-propionate Methyl p-hydroxybenzoate Butyl p-hydroxybcnzoate Wool Fat White Soft Paraffin EXAMPLE 18 An oil-in-water cream was prepared containing the following ingredients:

21-Desoxyprednisolone l7a-propionate 0.1% Cetamacrogol 1000 [.871 Cetostearyl Alcohol 7.2% White Soft Paraffin 15.0% Liquid Paraffin 6.0% Sodium Citrate 0.7% Citric Acid 0,5 7 Chlorocresol 015 Purified Water 68.55%

EXAMPLE l9 Antibacterial oil-in-water creams were prepared with similar compositions to that of the cream described in Example 18, but in which:

a. 3 percent of the water was replaced by 3 percent of 5-chloro-8-hydroxy-7-iodoquinoline.

b. 0.1 percent of the water was replaced by 0.1 percent of 2-bromo-2-nitropropane-1,3-diol.

c. 1.5 percent of the water was replaced by 1.5 percent of 5,7-dichloro-8-hydroxyquinoline.

d. 0.75 percent of the water was replaced by 0.75

percent of 5,7-dichloro-8-hydroxyquinoline.

e. 0.5 percent of the water was replaced by 0.5 percent of neomycin sulphate.

EXAMPLE 20 An ointment was prepared containing the following ingredients:

2lDesoxyprednisolone 17a-propionate Wool Fat White Soft Paraffin EXAMPLE 21 Antibacterial ointments were prepared with similar compositions to that of the ointment described in Example 20 and containing also 0.1 percent of 2-bromo- 2-nitropropane-l,3-diol, 0.75% or 1.5 percent of 5,7- dichloro-S-hydroxyquinoline 3 percent of 5-chloro-8 hydroxy-7-iodoquinoline or 0.5 percent of neomycin sulphate.

EXAMPLE 22 An ear drop was prepared by dissolving 21-desoxyprednisolone l7a-propionate 0.1 percent w/w in propylene glycol.

EXAMPLE 23 An aerosol spray was prepared by dissolving 2l-desoxyprednisolone l7a-propionate in industrial methylated spirit and hexylene glycol and adding chlorofluoroalkane propellants to give a composition containing the following ingredients:

21-Desoxyprednisolone l7a-propionate 0.1% Industrial Methylated Spirit 29.9% Hexylene Glycol 10.0% Freon 11 30.0% Freon 12 30.0%

EXAMPLE 24 An aerosol quick-breaking foam preparation was prepared containing the following ingredients:

ZI-Desoxyprednisolone 17a-propionate 0.1% Polawax 0.3% lndustrial Methylated Spirit 49.6% Hexylene Glycol 10.0% Purified Water 300% Freon 12 6.0% Freon 114 4.0%

We claim:

1. A therapeutic composition in a form suitable for topical administration which comprises an antiinflammatory effective amount of a compound of the formula in which R is a member selected from the group consisting of ethyl, n-propyl and isopropyl, in association with a pharmaceutically acceptable carrier.

2. A therapeutic composition according to claim 1 in which R is ethyl.

3. A method of treating a topical inflammatory condition which comprises the topical application to a subject suffering from said topical inflammatory condition of an anti-inflammatory effective amount of a compound of the formula the form of an ointment.

l l= l 

1. A THERAPEUTIC COMPOSITION IN A FORM SUITABLE FOR TOPICAL ADMINISTRATION WHICH COMPRISES AN ANTI-INFLAMMATORY EFFECTIVE AMOUNT OF A COMPOUND OF THE FORMULA
 2. A therapeutic composition according to claim 1 in which R is ethyl.
 3. A method of treating a topical inflammatory condition which comprises the topical application to a subject suffering from said topical inflammatory condition of an anti-inflammatory effective amount of a compound of the formula
 4. A method according to claim 3 in which R is ethyl.
 5. A therapeutic composition according to claim 1 in the form of a solution.
 6. A therapeutic composition according to claim 1 in the form of a suspension.
 7. A therapeutic composition according to claim 1 in the form of a cream.
 8. A therapeutic composition according to claim 1 in the form of an ointment. 